• Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Journal of the Acoustical Society of America

SECTION LISTING

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue

Apr 1942

Volume 13, Issue 4, pp. 337-392


The Measurement of Flow Resistance of Porous Acoustic Materials

Richard L. Brown and Richard H. Bolt

J. Acoust. Soc. Am. Volume 13, Issue 4, pp. 337-344 (1942); (8 pages) | Cited 9 times

Online Publication Date: 16 Jun 2005

Full Text: | Download PDF

Show Abstract
The flow resistance is one of the three physical parameters of a uniform, rigid, porous material which completely determine its acoustic behavior; for more complicated materials and sound absorbing structures the flow resistance gives at least some acoustic information. The specific flow resistivity or flow resistance per unit cube is given by the equation r  =  pAt/Vt, in which p is the pressure drop in dynes per cm2 across the thickness l cm of a sample of area A cm2 when a volume V cc of air flows steadily through the sample in a time t sec. An accurate method has been developed for obtaining r by direct measurements of the quantities p, A, t, V, and l. Using this method flow resistance measurements have been made on twenty‐four materials over a wide range of velocities. The measurements show that for nearly all materials there is a variation of flow resistance with velocity. For most materials the resistivity is constant below 0.1 cm per sec. but increases considerably at higher velocities. It is shown that previously described comparison methods, which have the advantages of simplicity and speed, might yield results in serious error unless certain suggested precautions are observed. As indicated previously, a direct correlation is found between the steady state flow resistance values and the resistive component of acoustic impedance for several materials. Analysis of the data also yields additional information bearing on the basic physical processes involved in the absorption of sound in these materials. In addition, the measurement of flow resistance has practical applications, such as the rapid routine checking of uniformity of samples of porous materials.

Acoustic Filtration in Parallel Conduit Structures

L. W. Labaw

J. Acoust. Soc. Am. Volume 13, Issue 4, pp. 345-352 (1942); (8 pages)

Online Publication Date: 16 Jun 2005

Full Text: | Download PDF

Show Abstract
The filtration characteristics of five Quincke‐Herschel tubes in series were measured in three ways: (a) by observing the ratio of the squares of the excess pressures at the end and beginning of the filter when terminated by a closed and open finite ending; (b) by observing the phase difference between these two pressures for the two cases in (a); and (c) by observing the true power transmission ratio with the filter terminated by an effectively infinite line. The experimental results are plotted with the corresponding theoretical curves. The number of experimental peaks in the transmission regions in (a) and (c), and the positions of the attenuation bands agree with the predictions of the theory. The values of the curve minima in the transmission bands are in excellent agreement up to 5000 cycles. The change of phase over the filter was also found to correspond closely to the theory.

Acoustic Filtration by Membranes

L. W. Labaw

J. Acoust. Soc. Am. Volume 13, Issue 4, pp. 353-359 (1942); (7 pages)

Online Publication Date: 16 Jun 2005

Full Text: | Download PDF

Show Abstract
This paper presents an experimental and theoretical study of the filtering action of a structure consisting of five stretched circular membranes equally spaced in an acoustic conduit, together with an experimental study of the effect on the transmission of puncturing the membranes with different sized holes. The stretched membrane filter is high pass, while the punctured orifices of sufficient diameter change the structure to a low pass type. This study shows that it is valid to assume plane wave propagation in the circular membrane filter up to 5000 cycles.

An Analyzer for Sub‐Audible Frequencies

H. H. Scott

J. Acoust. Soc. Am. Volume 13, Issue 4, pp. 360-362 (1942); (3 pages)

Online Publication Date: 16 Jun 2005

Full Text: | Download PDF

Abstract Unavailable

Relation of Audiogram Measurements to Hearing Aid Characteristics Based on Commercial Experience

Fred W. Kranz and Carl E. Rudiger

J. Acoust. Soc. Am. Volume 13, Issue 4, pp. 363-366 (1942); (4 pages)

Online Publication Date: 16 Jun 2005

Full Text: | Download PDF

Abstract Unavailable

Dynamic Auditory Localization

Adelbert Ford

J. Acoust. Soc. Am. Volume 13, Issue 4, pp. 367-372 (1942); (6 pages)

Online Publication Date: 16 Jun 2005

Full Text: | Download PDF

Abstract Unavailable

A Method for Measuring the Percentage of Capacity for Hearing Speech

Edmund Prince Fowler

J. Acoust. Soc. Am. Volume 13, Issue 4, pp. 373-382 (1942); (10 pages)

Online Publication Date: 16 Jun 2005

Full Text: | Download PDF

Abstract Unavailable

Experiments on the Pellet‐Type of Artificial Drum

Karl Lowy

J. Acoust. Soc. Am. Volume 13, Issue 4, pp. 383-388 (1942); (6 pages)

Online Publication Date: 16 Jun 2005

Full Text: | Download PDF

Abstract Unavailable

The Change of Phase Caused by Impedance Deafness

Karl Lowy

J. Acoust. Soc. Am. Volume 13, Issue 4, pp. 389-392 (1942); (4 pages)

Online Publication Date: 16 Jun 2005

Full Text: | Download PDF

Abstract Unavailable
back to top
RSS Feeds

Erratum: The Correlation Between Elastic Deformation and Vertical Forces in Lateral Recording (J. Acous. Soc. Am. 13, 284 (1942))

S. J. Begun and T. E. Lynch

J. Acoust. Soc. Am. Volume 13, Issue 4, pp. 392-392 (1942); (1 page)

Online Publication Date: 16 Jun 2005

Full Text: | Download PDF

Abstract Unavailable
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close